[Exim] How to close (expire) account?

With Exim 3.3x, what's the right and proper way to "close" a mail account
without actually removing the user from the passwd database? The behaviour
I want can be stimulated (more or less) by using the below exim filter as
.forward, but I'm looking for a simpler/more general/more correct way.

# Exim filter

seen mail from "Mail Delivery System <Mailer-Daemon@$domain>" subject
"Mail Delivery failed: Account expired" text "The following message was
not delivered, as account \"$local_part\" has expired" return message

--
- Toralf